Method of treating organic compounds



Patented Dec. 22, 1942 Winston n. Walters, mm, a. 1.. andlrancls Owen Rice, Silver Spring, Md; laid Walters asslum to said Bloc No Drawing. Application mm, 1m, Serial No. stem 11 Claims. (CL 2804!.)

This invention relates to. the treatment of ketones.

According to our invention, acetone is decomposed into ketene. Thermal processes for effecting this decomposition are known, but we have found that by using a relativelysmall amount of an activator, the rate of decomposition is increased and the decomposition may be carried out at lower temperatures. In our process the activator which is used is diacetyl.

The proportion of the diacetyl used as an activator may vary between about 0.11 per cent by volume to about 2.3 per cent by volume of the acetone to be decomposed, the preferred amount of activator being about 1.0 per cent. The decomposition varies with the amount of activator employed, being greater for larger percentages of activator. The temperature at which the decomposition is conducted may vary from about 500 centrigrade to about 540 centigrade. The pressure employed may vary from about one-tenth of an atmosphere to about onefourth of an atmosphere. While neither the temperature nor the pressure employed in the decomposition process is critical, especially at the upper limits of the ranges mentioned, we found that the rate of decomposition increases with increases in the temperature. Temperatures as high as 600 centigrade may be used. The decomposition proceeds very rapidly however, and shorter times of contact may be used. The time of contact to effect decomposition may extend over a period of from about three minutes to about ten minutes. Under optimum conditions most of the decomposition will take place in five minutes and in about ten minutes will be substantially complete.

The decomposition of acetone to ketene by known methods without the aid of a catalyst or activator requires high temperatures. At high temperatures reaction is dimcult to control. We 1 have found that if the decomposition is carriedof diacetyl, 31.9 per cent of the acetone decomposed to ketene after a time of contact of seventeen minutes. When acetone was decomposed under the same conditions without the use of diacetyl as an activator only 14.8 per cent decomposed into ketene. Approximately the same results were obtained when the acetone was heated to about 506 centigrade and again to about 540 centigrade.

In another example, acetone was heated under a pressure of one-seventh of an atmosphere to about 5% centigrade in the presence of 1.191 per cent by volume of diacetyl. After two and a half minutes 8.2 per cent acetone decomposed to ketene. Under the same conditions without the use of diacetyl as an activator only 3 per cent of the acetone decomposed into ketene.

In still another example, acetone was heated under a pressure of 0.13 of an atmosphere to about 526 centigrade in the presence of 2.3 per cent by volume of diacetyl. After a contact time of seventeen minutes, 45.3 per cent acetone decomposed to ketene. When acetone was heated under the same conditions, but without the use of diacetyl as an activator, only 15.5 per cent of the acetone decomposed to ketene. We have found that when the percentage of dlacetyl employed as an activator is increased above about 2.8-per cent by volume the rate of decomposition is not materially accelerated.

In all of the above examples, the reaction product may be treated to separate the ketene and the unconverted acetone may be recycled for further treatment in the presence of added diacetyl. In commercial installations, the output of a thermal decomposition process for converting acetone to ketene may be increased ap- 1.0 per cent by volume 01 diacetyl as an activator to accelerate the decomposition of the acetone to ketene.

acetyl as an activator to accelerate the decomposition of the acetone to ketene.

3. A method of decomposing acetone to ketene which comprises heating acetone to about 526 C. under a pressure of about one-fourth of an at-\ mosphere in the presence of about 0.94 per cent by volume of diacetyl as a promoter to accelerate the decomposition of the acetone to ketene.

4. A method of decomposing acetone to ketene which comprises heating acetone to aboute 526 C. under a pressure of about 0.13 of an atmosphere in the presence of about 2.3 per cent by volume of diacetyl to accelerate the decomposition of the acetone to ketene.

5. A method of decomposing acetone to ketene which comprises heating acetone in the presence of an appreciable amount up to about 2.3 per cent by volume of diacetyl at an appreciable pressure up to about .26 atmosphere.

6. A method or decomposing acetone to ketene which comprises heating acetone in the presence of an appreciable amount up to about 2.3 per cent by volume of diacetyl at a temperature of at least 500 C.

7. A method of decomposing acetone to ketene which comprises thermally decomposing acetone in the presence of between about 0.11 and 2.3 per cent by volume of diacetyi to form ketene.

8. A method of decomposing acetone to ketene which comprises heating acetone in the presence of between about 0.11 and 2.3 per centby volume or diacetyl at a temperature of between about 500 C. and 540 C.

9. A method or decomposing acetone to ketene which comprises heating acetone in the presence of between about 0.11 and about 2.3 per cent by volume of diacetyl at a temperature at between about 500C. and about 540 C. and at a pressure from about one-tenth to about one-fourth of an atmosphere.

10. A method of decomposing acetone to ketene which comprises heating acetone in the presence of between about 0.11 and about 2.3 per cent by volume 01' diacetyl at a temperature of between about 500 C. and about 540 C. at a pressure from about one-tenth to one-fourth 01' an atmosphere and for about three to ten minutes.

11. In the process of thermally decomposing acetone to ketene the step of carrying out the thermal decomposition in the presence of an appreciable amount of diacetyl up to about 2.3 per' cent by volume.

WINSTON D. WALTERS. FRANCIS OWEN RICE. 

